1) Place an oven rack in the lower third of the oven. Preheat the oven to 220°C/gas mark 8.
2) Rinse the poussins and pat dry with paper towels. In a small bowl, mix together the olive oil, shallots, orange zest, lemon zest, thyme, mint, salt and pepper. Rub two tablespoons of the zest mixture over the skin of the poussins. Place the remainder of the zest mixture under the skin and into the cavities of the poussins. Using kitchen string, truss the legs together. Place the hens in a shallow 23cm x 33cm baking dish.
3) Add the chicken stock, Marsala wine, lemon juice, orange juice and cranberries to the pan. Put the birds in the oven and roast for 30 to 35 minutes, or until the leg juices run clear. Remove the poussins and set aside.
4) Place the plain flour in a small saucepan. Whisk in the pan juices and bring to a boil over medium heat. Reduce the heat and simmer for 8 to 10 minutes until slightly thickened. Whisk in the butter and season, to taste, with salt and pepper.
To serve, remove the kitchen string and place the poussins on two serving plates. Drizzle with the citrus-herb sauce.
Cook's note: Reserve 60ml of the citrus-herb sauce for Giada's Crouton Salad recipe.